Mycobacterium recombinant vaccines.

Intracellular diseases are difficult to treat and constitute a major problem for modern medicine. In this type of diseases, a TH-1 immune response favors protection, while a TH-2 response is detrimental to the host. Current vaccines are using antigens to initiate an immune response regardless of its nature and its mechanism. New vaccines are designed to combine selected antigens with potent adjuvants to stimulate the appropriate pathway of the immune system and deliver a lasting protective immunity. The Mycobacterium recombinant vaccine system for treatment of intracellular diseases utilizes antigen delivery systems in the form of non pathogenic Mycobacterium strains, genetic transfer systems in the form of cloning and expression vectors, and related technologies to provide products containing non toxic immuno-regulating Mycobacterium adjuvants, non toxic immuno-stimulating exogenous antigens specific for a variety of diseases, and non toxic amounts of cytokines that boost the TH-1 pathway. The cloning and expression Mycobacterium vectors include both pAL5000-based extra-chromosomal and D29-based integrative vectors.

Relationships between titers of antibodies immunoreacting against glycolipid antigens from Mycobacterium leprae and M. tuberculosis, the Mitsuda and Mantoux reactions, and bacteriological loads: implications in the pathogenesis, epidemiology and serodiagnosis of leprosy and tuberculosis.

Analysis of cell-mediated immunity [(CMI) as judged from the Mantoux, Fernandez, and Mitsuda reactions and the presence of granulomas in biopsy material] against humoral immunity (measurements of anti-PGL-I, PGL-Tb1, and SL-IV IgG and IgM antibody titers by ELISA) were performed in selected human populations. The investigations yielded data indicating that humoral (B-cell) responses preceded protective CMI in both tuberculosis and leprosy. The B-cell responses were unrelated to (unfavorable) cell-mediated delayed-type hypersensitivity (DTH). Notwithstanding the difficulty in inferring sequential events from studies in humans, it was shown that in humoral responses there was an initial rise of specific IgM immunoglobulins that switched afterward to IgG production during subclinical tuberculosis and leprosy infections. In patent tuberculosis disease the IgM-to-IgG switch was observed in the majority of patients; in patent leprosy disease the switch was impaired in the majority of patients. The clinical, immunological, and laboratory data indicated that the B-cell responses were suppressed as protective CMI was re-established in the patients during the protracted subclinical infection. According to the data, the diagnosis of subclinical tuberculosis and leprosy may be accomplished using ELISA. The yearly risk of tuberculosis in apparently healthy persons but with significant antibody titers was estimated at 44%; the yearly risk for leprosy has not yet been established. The clinical, epidemiologic, and diagnostic implications of these findings are discussed.

Antigenicity and specificity of selected glycolipid fractions from Mycobacterium tuberculosis.

Antigenicity of Mycobacterium tuberculosis glycolipids polyphthienoyl trehalose (PPTR), phenolic glycolipid (PGL-Tb1), tetraacyl trehalose-2'-sulphate (SL-I) and diacyl trehalose-2'-sulphate (SL-IV) was examined in rabbits. PPTR did not induce production of IgG antibodies in rabbits, while PGL-Tb1, SL-I and SL-IV glycolipids were efficient in this respect. Immune sera raised in rabbits immunoreacted exclusively with the corresponding antigens, which indicated that they were remarkably specific. Specificity of the immune sera was further examined using crude extracts of representative strains of 39 mycobacterial species, and the data showed that these immune sera reacted only with extracts of M. tuberculosis and M. africanum. An antiserum raised against whole cells of M. leprae immunoreacted with the purified SL-IV antigen from tubercle bacilli.

Comparative intracellular growth of difficult-to-grow and other mycobacteria in a macrophage cell line.

We have recently developed a murine macrophage cell line (J-774) model which permits the growth of various mycobacteria (8). The purpose of the present investigation was to compare the intracellular growth of various difficult-to-grow mycobacteria (Mycobacterium paratuberculosis, M. ulcerans), and other pathogenic (M. tuberculosis H37Rv, M. kansasii, M. bovis) and nonpathogenic or avirulent (M. tuberculosis H37Ra, M. bovis BCG, M. gastri) mycobacteria. Electron microscopic studies were also performed to elucidate whether the formation of an electron-transparent zone (ETZ) around phagocytized bacilli was linked to their intramacrophagic survival. Furthermore, the comparison of intracellular growth of a pathogenic (M. kansasii) and nonpathogenic (M. gastri) mycobacteria sharing the same phenolic glycolipid antigen at their surface (Mycoside-A, 5), suggested that these antigens did not play a primary role in intracellular survival and multiplication of these bacteria. Also, we were unable to propagate M. ulcerans inside J-774 macrophages, which were massively lyzed after infection (due to a characteristic toxin secreted inside the macrophages?). These results are discussed in terms of the validity of the J-774 model for studying intracellular growth of mycobacteria.

Restriction map of mycobacteriophage D29 and its deletion mutant F5.

A physical map of mycobacteriophage D29 was constructed, including positions for 25 restriction sites for 9 endunocleasic enzymes. D29 DNA contains about 48 150 bp. Analysis of a deletion mutant (F5) has allowed to determine the location of two non essential regions in the genome, allowing further insertion of foreign genes and construction of cosmids.

Ability of smooth and rough variants of Mycobacterium avium and M. intracellulare to multiply and survive intracellularly: role of C-mycosides.

A spontaneous rough (Rg) mutant of M. avium ATCC 15769 was mutagenized using N-methyl-N-nitro-nitrosoguanidine (MNNG). Out of 54 clones initially chosen on the basis of their morphological appearance on the 7H11 agar, seven Rg clones were selected on the basis of their response to current biochemical tests, and were later characterized for their cell wall amphiphilic contents (analysis of loosely-bound surface lipids for mycosides, peptidolipids, phospholipids, and mycolic acids by thin layer chromatography, and fatty acids by gas chromatography), and ability to grow intracellularly inside J-774 macrophages. A parallel study was also performed on a previously reported Rg mutant of M. intracellulare serovar 20 (W.W. Barrow and P.J. Brennan, J. Bact. 150 (1982) 381-384) which lacked the ability to synthesize mycosides C (MYC-). The results obtained were compared to parental smooth (Sm) colony-types of the respective M. avium-intracellulare strains. Our results showed that neither the ninhydrin-reacting lipids (probably peptidolipids) nor the glycopeptidolipids (mycosides C) were primary factors responsible for the intracellular survival and multiplication of these bacteria. Ultrastructural studies showed that although the polysaccharide-rich outer wall layer (POL) in case of MYC- Rg strain was not uniformly distributed and contained blebs, these bacteria formed the characteristic electron-transparent zone (ETZ) upon phagocytes by macrophages. Furthermore, the multiplication of MYC- Rg strain inside macrophages did not result in intracellular selection of MYC+ bacteria, nor in Rg to Sm transition.

Action of antituberculous and beta-lactam drugs (including imipenem) against extra- and intra-cellularly growing Mycobacterium avium-intracellulare.

The extracellular and intracellular activities of 4 antituberculous drugs (rifampicin, streptomycin, ansamycin and kanamycin) and 7 beta-lactam antibiotics (penicillin G, amoxycillin, carbenicillin, ticarcillin, ampicillin, cloxacillin and imipenem) were determined against the bacteria of the Mycobacterium avium complex (MAC). The extracellular activities were determined against 14 strains by the broth-dilution method, whereas the intracellular activities were determined against type strain ATCC 15769 multiplying actively inside murine J-774 macrophages. Six of the beta-lactam drugs (except the beta-lactamase-stable drug imipenem) were also used in association with the beta-lactamase inhibitor clavulanic acid. Our results showed that the screening of MAC strains against beta-lactams may be useful, and that correlation of usual in vitro minimal inhibitory concentrations with the intracellular activities of the same drugs against pathogenic mycobacteria, whenever feasible, would be the method of choice to designate the therapeutic protocols against these intracellular pathogens.

Structure of the cell envelope of Mycobacterium avium.

In this report the cell wall of Mycobacterium avium is shown as a triple-layered structure where the outermost layer was stained by the ruthenium red staining for polysaccharides. The outermost layer hindered the diffusion of chemotherapeutic agents across the wall thus causing multiple drug-resistance by exclusion. The concerted electron microscopy and chemical analysis of chloroform-methanol and Triton X-100 extracts indicated that the outer layer was made of diverse amphiphil glycolipids (mycosides C, glycolipids, peptidolipids, phospholipids) that formed a matrix in which proteins were embedded. The examination of a spontaneous rough mutant indicated that mutations blocking the synthesis of one or several of the amphiphils must leave unsubstituted mycolic acid residues, thus causing surface hydrophobicity and roughness. Judging from our data, a model describing the overall cell envelope of M. avium was proposed. From the comparative analysis of M. avium, its spontaneous rough mutant, and its spheroplasts, some of the functions of the outermost layer were disclosed.

Macrophage interaction with mycobacteria including M. leprae.

Resistance properties of pathogenic mycobacteria to macrophage bactericidal activity seems to be due mostly to the composition and constitution of their cell walls. In the case of Mycobacterium tuberculosis, sulfatides and polyglutamic acid could be implicated in the phenomenon of fusion inhibition between phagosomes and lysosomes. M. leprae and M. lepraemurium, which do not seem to inhibit fusions are protected by a thick electron transparent zone (ETZ) that seems to be composed of mycosides. This layer would inhibit lysosomal enzyme diffusion inside phagosomes. As ETZ does not exist in mycobacteria before their phagocytosis, we have tried to see when and how it is formed inside macrophages. We have compared ETZ formation in M. leprae and M. avium which both contain mycosides. These two species were allowed to be phagocytized by mouse bone-marrow derived macrophage and samples were taken for electron microscopy during the first hours of phagocytosis and also during several weeks of incubation. In M. avium ETZ appeared within 1 to 2 hours after phagocytosis. It seems to be formed by a sort of swelling of the thin electron transparent layer of the bacterial cell wall. This swelling occurs only in regions where the external polysaccharide layer of M. avium starts to disappear. After 1 to 3 hours, this layer was completely absent and all bacteria were enveloped in a thick ETZ. In M. leprae, the ETZ is also formed within one hour after ingestion. However, the presence in some bacteria of a very thin dense layer located at the original place of the outer dense layer of the cell wall does not fit well with the idea of ETL swelling. In addition, the appearance of a thick dense layer located between the ETZ and the phagosome membrane is not yet understood. The ETZ formed also rapidly in macrophages infected with heat killed cells of M. avium or M. leprae. This shows that its formation does not require the active participation of the bacterium. As already proposed ETZ seems to lessen considerably the diffusion of lysosomal enzymes towards the bacterium in both species. In M. leprae it seems especially efficient because despite acid phosphatase activity found in many phagosomes, neither the number of bacteria per macrophage nor their state of degradation changed during 3 and a half months of macrophage culture.(ABSTRACT TRUNCATED AT 400 WORDS)

Phagocytosis of Mycobacterium leprae and M. avium by armadillo lung fibroblasts and kidney epithelial cells.

In vitro cell cultures of lung fibroblasts and kidney epithelial cells were established from a freshly killed armadillo and were inoculated with Mycobacterium leprae. Lung fibroblasts were also inoculated with M. avium. Phagocytosis was allowed for 6 h at an input of about 50 bacilli/cell, and the ultrastructure was then studied at 24 and 48 hours, and 4, 7 and 10 days. Following observations were made: 1. Armadillo cells could be maintained for nearly 3 months. 2. Both lung fibroblasts and kidney epithelial cells phagocytized M. leprae at a high rate. 3. Lung fibroblasts also phagocytized M. avium but with a rate much slower than M. leprae. 4. Both in M. leprae and M. avium, an electron-translucent halo surrounded the ingested bacteria within hours of phagocytosis, and this halo appeared to lessen the diffusion of lysosomal enzymes towards the bacterium. 5. M. leprae was often phagocytized in clumps of 3 to 5 bacilli, which separated inside the cell resulting into small individual phagosomes with a single bacterium. 6. In our experimental conditions, there was no evidence of multiplication for both M. leprae and M. avium. 7. The phagocytized bacilli slowly degraded with longer incubation periods, however, the undigested cell bodies remained inside the phagosomes.

Reduction of potassium tellurite and ATP content in Mycobacterium leprae.

The purpose of this investigation was to examine those properties of Mycobacterium leprae which might be useful in estimating the heterogeneity of the bacterial populations harvested from the tissues of experimentally infected armadillos. The following technical procedures were applied: fluorescent microscopy on smears stained by an Auramine O-Ethidium bromide dual procedure, fine structure observation of ultrathin sections, reduction of potassium tellurite as observed under the electron microscope, and ATP content of the bacteria. The quantitative data from these procedures was compared to the morphological index, and it was shown that the results did not correlate. However, the study of tellurite reduction was interesting because this technique may prove useful in evaluating the contamination of M. leprae preparations by host tissues. More significant was the fact that M. leprae reduced tellurite. Even though the reduction was at a very low efficiency under the conditions described, it would be possible to use this technique to investigate the effects of several substrates on the respiratory activity of the leprosy bacilli.

Use of cetylpyridinium chloride and sodium chloride for the decontamination of sputum specimens that are transported to the laboratory for the isolation of Mycobacterium tuberculosis.

A method is presented for the decontamination, liquefaction, and concentration of sputum specimens that are in transport more than 24 h. The method is inexpensive, and culture results compare well with those obtained with the accepted N-acetyl-L-cysteine and sodium hydroxide method for the isolation of tubercle bacilli. The working solution, 1% cetylpyridinium chloride and 2% sodium chloride, is mixed in equal volumes with sputum before the specimens are shipped. Tubercle bacilli remained viable after 8 days of exposure to this solution. Only Lowenstein-Jensen medium was used because the cetylpyridinium chloride in the inoculum remains active on 7H10 or other agar base media and partially inhibits the growth of tubercle bacilli.